


Diamond Days

by amamiya_toki



Series: 輝く、僕と私の日々 [1]
Category: IDOLiSH7 (Video Game)
Genre: Alternate Universe - Canon Divergence, Alternate Universe - Normal High School, Bedroom Sex, Established Relationship, F/M, Gender or Sex Swap, Masturbation in Bathroom, Mutual Masturbation, Twincest
Language: English
Status: Completed
Published: 2017-07-11
Updated: 2017-07-11
Packaged: 2018-11-30 18:58:26
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 13,982
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11469678
Author URL: https://archiveofourown.org/users/amamiya_toki/pseuds/amamiya_toki
Summary: Set in a what-if world where Tenn does not choose to follow Kujou and is still living with his family. Nanase Tenn is now in his last year of high school. While he is like any other student, having his beloved sister by his side makes these days truly precious, even more than diamonds.





	Diamond Days

**Author's Note:**

  * Inspired by [女体！アイナナLOG③](https://archiveofourown.org/external_works/306231) by Nezu Dango (ねずだんご). 



> Back when Nezu Dango-san uploaded this on facebook, sometime around the beginning of this year I believe, I enthusiastically went "PLEASE LET ME WRITE THIS" (not exact words) as I always do.
> 
> As mentioned, this is about Tenn's life if he did not choose to leave with Kujou. I haven't written smut/R18 stuff in ages so pardon me.
> 
> I began writing this in February for a week, stopped until late May and only finished this afternoon; it took me the whole evening to get the editing done and it's about half an hour to midnight. It's the longest thing I've written in ages, I think.

The boisterous beeping of his alarm clock would be the first thing that registers in Nanase Tenn's senses when he wakes up every morning.

He would stretch his hand out to push the button on top of the device, to turn it off and spare his ears from having to listen to any more of that annoying sound. Following that, he would sit up with a grunt, stretching his arms high above his head. He had yet to shake off the lazy, lethargic feeling of having been asleep, but he was awake and did not feel the impulse to lie down again.

Pushing the covers aside, he got off the bed and made his way down from his room to the bathroom to wash his face. As he did he would walk past the kitchen where his mother was already preparing breakfast. She would greet him with a big, beaming smile as he offered her his morning greetings. She would return the greeting with her own, her usual upbeat cheer evident in her voice.

As he was washing his face, his father would come in looking as if he was sleepwalking. Unlike his wife the man grunted his greeting in a grouchy tone, rubbing his unshaven chin as he dragged his feet in a sluggish pace.

When Tenn was done, he would return to his room to change into his school uniform. However, as he was making his way back, his mother called out to him with her usual request. "Tenn-chan, could you go wake your sister for me?"

He would have done that, even if he was not asked to.

His school uniform was of the blazer variety. Changing out of his pyjamas, Tenn would first put on the crisp white shirt, slipping his arms into the long sleeves and doing up each button diligently. Next were his trousers, which he would tuck his shirt into before buckling the belt and slipping on his socks. He would then do his tie, tying the knot skillfully with nimble fingers. In addition to the standard-issued winter uniform he would wear a knitted vest beneath his blazer jacket, the latter he would only put on before he leaves home for school. It may be the first week of April but the weather was still too chilly for his liking.

Once he was done, it was time to wake his twin sister up.

Unlike her older brother, Nanase Riku was the kind of teenager who enjoyed sleeping in and would return back to bed after being woken up, either by her own alarm clock or another person.

When Tenn entered her room, she was still snoozing, comfortably cuddling her body pillow to her chest as she slept peacefully. It seemed that she was having a dream, and a rather happy one at that as well, judging from the blissful expression on her face.

"Riku, wake up. We'll be late."

"Tenn-nii, I can't eat any more of those yummy doughnuts…"

So it was that kind of dream again; Tenn did not know if he should smile or sigh.

"Stop talking nonsense in your sleep and get up already. Come on, wake up. You have class duty today, don't you?"

"Five more minutes…"

"No can do."

"Mmmm…" Ignoring him, she simply tossed in her bed to face the other way.

Tenn sighed. Stubbornness was a trait that they both shared, to a horrifyingly similar degree, but it was not a good thing when it came to wanting to be spoilt.

"Riku," he whispered into her ear gently. "If you don't get up now, I won't treat you to those strawberry tarts that we were going to buy after school today."

And if it was one thing about the teen named Nanase Tenn that should be made known to everyone, he does not make empty threats. His sister should and does know that better than anyone else.

She sat up with a start and would have hit Tenn's head with her own if the boy had not moved away in time. "I'm awake!"

Her reaction was so adorable, and he could not help but laugh at her. She pouted at him, her cheeks puffing up like a ripened tomato, but just for a moment.

"Good morning, Tenn-nii." She smiled at him, stretching her arms out for a morning hug.

Tenn obliged, but did not allow their chests to touch. Even if she was his sister it was awkward to feel her bare breasts beneath the thin cotton pyjamas she wore, in more than one way. "Good morning, Riku."

"Even though it's early in the morning, Tenn-nii is handsome and cool as usual."

"Riku too, you're as cute as always. Although, I can't say the same for that atrocious bed-hair of yours."

"Hey!"

"Dad should be done with the bathroom by now, so you can have it all to yourself. Make sure to hurry or we'll be late."

"Okay!"

Before heading down to breakfast, Tenn would grab his school bag and blazer jacket from his room. These he would place on the couch of the house's combined living-dining area before rolling up his sleeves to help his mother set the table.

No breakfast on two consecutive days was the same in the Nanase family; today was a Western-style breakfast with two eggs done sunny-side up, a slice of toast, two sausages, a salad on the side and a warm cup of creamy corn soup. The day before had been Japanese-style with mackerel marinated in teriyaki sauce and grilled, the favourite fish of their father's side of the family.

As he was setting the plates down, his father would come in dressed up for work with the newspaper in hand, taking his usual seat next to his wife and opposite Tenn's. Riku would come bumbling in later in her school uniform: white shirt with the school's ribbon tie, pleated skirt over black tights and her favourite cream-coloured cardigan. Like Tenn, she dropped her bag and blazer jacket onto the couch before sitting down at the table.

"Good morning, Mom and Dad!"

"Good morning, Riku-chan… oh, my. Your hair's in quite a mess."

"I'll have Tenn-nii help me with it later!"

"Relying on Tenn again… you're already in your third year of high school, you know?"

"It's fine, Dad. I'm helping Riku because I want to."

"See? It's not like I'm forcing Tenn-nii to do it for me or anything like that!"

"I'm glad to see that the both of you are so close; we raised you that way after all," their mother sighed as she joined the family at the table. "But I really worry that neither of you would be able to find a girl or boyfriend like this."

"You're thinking too much, dear. They should be thinking of college first."

"But don't they say that romance blooms in the springtime of youth? We too were in high school when we first began dating, you know."

The man cleared his throat loudly, his way of hiding his embarrassment. "The food will get cold. Let's eat."

"Really, it won't hurt for you to be honest, honey. Well then, let's tuck in."

"Thank you for the food!"

The food was warm and delicious, even more so because the entire family was enjoying it together. However, there was barely much time for the children to partake in it leisurely, as they had to rush off to school. Tenn finished first, gathering his dishes and placing them in the sink as he thanked his mother for putting in the effort to make this meal for them. He returned to the bathroom to brush his teeth, and Riku followed soon after.

When she was done, Tenn was already waiting for her in the living room with her hairbrush and assortment of hair ties and scrunchies, which was kept in one of the cabinets of the television stand.

Unlike Tenn who had thinner strands of hair, Riku's were visibly thicker. That was why he used a brush rather than a comb to straighten and untangle the messy red locks. When he was done, he would get her to choose something to tie her hair up with.

"The pink scrunchie again?" Tenn raised her eyebrow at her choice. "You really like this one, don't you?

"Of course! It's Tenn-nii's colour, after all!"

Tenn could not help but to smile at that, as he tied her hair in her usual low ponytail. However, because her hair was quite short, it was not as long as the word would describe or imply it to be. To him, it resembled more of a duck's bottom instead, but he would never say it out loud because it would make Riku pout at him again.

With that deed done, it was time to leave for school. They commuted to school by bicycle: Tenn pedalling and Riku seated behind him. Tenn's backpack and their wrapped lunchboxes would be placed in the basket at the front, while Riku balanced her standard-issue school bag on her lap. To make sure that she would not slip or fall off when the bicycle rolls over a bumpy section of the road, he would have her to hold onto him with her arms around his torso.

"Mom and Dad; we'll be off!"

"Riku, don't forget to put on your face mask and bring your inhaler!"

"I did! Dad, enjoy your business trip to Hokkaido!"

"Have a good day at school!"

The journey was a short fifteen minute's ride through the town and up the smooth slope where their school was located. Along the way, they would pass the shopping district and the fashion street, where many small shops and cafes were located. It was a popular after-school hangout for the students who studied nearby. There were occasional times when Tenn and Riku would stop by on their way home, especially to their favourite patisserie for cakes, tarts and treats.

As they made their way to school, the twins would be engaged in a casual conversation, sharing their opinions about the people they know and their own experiences amongst many topics. Often, Riku would be the one talking and Tenn either listening or reply to her.

Today, however, began on a rather serious note.

"Say, Tenn-nii, I was thinking about what Mom said earlier."

"About what?"

"About us... you know, finding our significant others."

Perhaps it was due to them approaching the pedestrian crossing, or Tenn feeling his heart sink, but he pulled the brakes of his bicycle a little harder than usual. The vehicle came to a sudden, but smooth stop.

Truth to be told, Tenn had been bothered about that matter. Both him and Riku were going to be eighteen in less than three months' time, yet neither of them has actually talked about romance and dating on a serious note. It had always been a topic brought up in casual conversation, stemming from Riku's love of romance novels.

"What about that?"

"I was just wondering, you know... if you intend to get a girlfriend. I mean, you're popular with the girls, aren't you? Our school has more girls than boys, and many of them are really cute and pretty. I hear them talking about you all the time, plus girls from other schools seem to know about you, too. It won't be strange if you have someone that you like and would start dating her... and that kind of thing."

"What about you, Riku? Don't you want to consider dating someone?"

"Me? I don't need to." Her arms that were wrapped around him tightened, just a little. "After all, I have Tenn-nii by my side, and that's all I need."

"... Is that so?"

Hearing that was more of a worry than a relief to Tenn.

In what way did Riku mean by that? If anyone who knew them had to guess, they would presume that she meant it as it was: she felt at ease just by him being there, physically, with her. After all, even when they were children, they were almost inseparable. The long durations that she spent in the hospital made brought them even closer, as they always looked forward to the time they got to spend with one another.

Because of this, he believed that he did not need friends or anyone else to be close to: all he needed was Riku.

If only his feelings and thoughts now were that simple.

"What about you, Tenn-nii? You haven't answered my question at all."

"It's the same for me. All I need is Riku."

He could not see her expression, but he could feel that she was radiating with glee.

It was not long before their school came into view, and as they entered the gates they heard a familiar voice call out to them.

"Nanase-kun! Riku-san! Good morning!"

"Tsumugi-chan!" Riku waved to her classmate and only friend, as she waited for the bicycle to come to a halt before hopping off.

"Good morning, Takanashi-san. How many times have I told you before that you can call me by my given name?"

"No, no, it's fine. I don't want to be an enemy of your secret fan-club."

Takanashi Tsumugi had been attending the same school as Riku since middle school, for Tenn since elementary school. She had been nominated the class president of Riku's class since her first year and had taken it upon herself to deliver handouts to the redhead when she was absent from school. She would even drop by their home or the hospital to visit her and check up on her. This continued until they had graduated from middle school, and when it was known that they attended the same high school the pattern continued. Tenn and Riku had never been put in the same class, so he felt bad having to rely on someone else. However, she had gained his trust and became the only other person he can entrust Riku to in his absence.

On a personal basis, Tenn was not close with her as Riku was, despite working closely with her on the student council since their first year of high school. However, he does consider her a friend.

In fact, she had also become a friend of the family; not just her but her father, Takanashi Otoharu, as well. Tenn first met him when the man was trying to scout him as an idol for his agency while he was out shopping with their family, only to discover after looking at his name card that he was the father of Tsumugi. As both Otoharu and their father loved music, they formed a quick bond and became friends, leading to the Takanashi family being invited to meals with the Nanase family, especially during holidays like Christmas or Golden week.

"Well then, Tenn-nii! I'll be going now!" After retrieving her bag, she saluted in what Tenn felt was an adorable manner. "I'll see you during lunch!"

"Take care." He waved farewell to her before pedalling over to the parking area.

When he unloaded his belongings, he noticed that Riku had forgotten her boxed lunch. Fortunately, he had nothing to do with the student council this morning so he could drop it off at her classroom on his way to his own.

As he made his way to the main entrance to change his shoes, some members of the track club happened to enter right before him. They were chatting noisily, having just finished their morning practice. It was still early and most students have yet to arrive, so there were only them and him at that enclosed area. Because of that, he could clearly hear what they were talking about.

"So it's true that that Nakamura is dating Satomi-chan from class 2-D?"

"Yeah, if you'd believe it. Who'd think that such a pretty girl would end up with a weeb like that?"

"It's not fair!"

"I know, right? If someone as ugly as him can get a girlfriend, why are we all still single, I wonder. There are so many girls in our school, too."

"Didn't you say that you were aiming for Hazuki-senpai from class B last week?"

"Yeah, but it turns out that she has a boyfriend already, and from that elite all-boys school over the other side of the station, too!"

"Wow, seriously? It's nice being an elite; you can get any girl you want just by looking their way."

"What about you? Isn't there anyone around here who caught your fancy?"

"Hmm... ah! I know! What about Nanase-senpai?"

Tenn was about to leave, as he had no interest in their conversation, but hearing his family name caught his attention. As far as he knew, only he and Riku bore that name in the entire school.

"The little sister from our captain's class, you mean? The one who is always hanging around Takanashi and the rest of the student council."

"Yeah! She's pretty cute, isn't she?"

"She doesn't look like she has a boyfriend too. Plus, that bust size ain't bad."

"You're saying that kind of things out loud?"

Tenn felt an eyelid twitch. How dare they look at and speak of Riku in that manner? However, he knew better than to start a fight over something this petty.

"Say, say. She doesn't look like the type who had done that sort of thing, has she?"

"That chick does give off a pure image, after all. What, don't tell me you're going to try hitting on her or something?"

"I mean, she isn't going out with anyone now, right? That means that it's no one's business if I wanna make her my girl, so I think I will."

"You better not try. Haven't you heard about her guard dog?"

"Dog? Our school forbids us to bring our pets, you know."

"I don't mean a literal one, you moron! I was referring to the older Nanase; her older bro— eek!"

Tenn made his presence known to them by stepping out of hiding, giving them a glare so deadly the two boys nearly peed their pants.

He did not have to say or do anything to get his intentions across.

"H-Hey, let's go." The one who had been interrupted by Tenn's presence grabbed his friend by the arm, pulling him away to escape from what could have escalated into something troublesome.

After they were out of his sight, Tenn relaxed his shoulders, heaving a sigh.

This was not the first time something like this happened, but that did not stop people from saying things of that nature. Because Riku had missed many days of school in her first year, many consider her to be some sort of phantom: unknown and mysterious. As a result, there were a lot of rumours about her which was no doubt unpleasant. It was likely that the girl herself was unaware of this.

Brushing the matter aside, Tenn had to head up to her class to pass her that boxed lunch. Along the way, he passed some girls from the brass band club who were giving him the usual stares. It was obvious that they were members of that so-called secret fan-club Tsumugi had mentioned on several occasions.

Their gazes were so intense that it was uncomfortable, but he chose to ignore them as he continued walking in his relaxed but confident gait.

At this time of the morning, there were few people around. Those who were present either had club activities or morning duties. That was why when he opened the door to her classroom, he was surprised to see someone speaking to her.

Nanase Tenn prided himself as someone who could read the mood. There was no doubt that he had just interrupted what was about to be a confession from her male classmate, whom he recognised as the ace of the basketball team who was in his class the previous year, to his younger sister. Despite the twinge of annoyance he felt in his chest, he would have had the sensibility to leave them be, knowing that she would turn him down. However, he could not disregard the item the male held in his hand.

"I'm sorry, but please refrain from giving Riku flowers? She's sensitive to allergens, you see, and the pollen from the flower could aggravate her condition."

"I-It's just a flower! How bad can it get?"

If Tenn was not a person of great self-control, he would have landed a punch into that smug mug. This ignorant fool... "During an allergic reaction, some parts of her body swell up, especially her throat which causes breathing difficulties. There are medications for that, but if it is bad enough she would have to be hospitalised. In the worst scenario, she would suffocate. I hope you can understand."

Fortunately, Tenn's brief explanation was sufficient in conveying his point. The student understood what he implied as well, which made him anxious.

"I-I'm sorry, I didn't know..." At least he had the decency to apologise before stumbling out of the classroom.

"Riku, are you okay?"

"I'm fine! Just a bit surprised, that's all. I mean, it's the first time that that person ever spoke to me. I wonder what it was that he wanted to talk to me about..."

Tenn let out a sigh. As a man, he could not help but have pity for the classmate who made his escape.

"Speaking of which, Tenn-nii, why are you here?"

"You forgot your lunch. Here."

"Oh! Thanks a lot, Tenn-nii!"

"Would you be eating with Takahashi-san today?"

"Tsumugi-chan said something about helping with home economics club, so I'll be by myself today. How about you join me, Tenn-nii?"

"I don't mind, but where shall we eat?"

"I want to eat in the schoolyard! At our favourite place by the fountain!"

Tenn paled at that suggestion. "It's still spring, you know? Are you sure you're okay being out in the open in this season?"

"Sheesh, you worry too much, Tenn-nii. I can go around in school without a face mask on, so I'll be fine!" She gave him a confident look, which through his rose-tinted vision, never fails to appear as adorable.

"If you don't feel well, make sure to let me know right away."

"Yes, sir!"

"Promise?"

"Promise!"

"Good." Tenn gave her a pat on the head before he turned to leave. "I'll see you later."

The rest of the day went by as per normal. Morning lessons breezed by quickly. Tenn listened to each word attentively, taking down notes to revise at a later time. On Fridays, his class had Japanese history, physical education, mathematics and English before lunch.

"And that's all we have for today. Complete the handouts that were passed out earlier over the weekend by the next lesson."

The English teacher collected her books after giving her instructions. The moment she shut the door behind her, the students in the classroom began preparing for their well-deserved lunch break. Not everyone brought their own lunches, opting to either eat the cafeteria or buy bread from the shop.

Tenn retrieved his boxed lunch from under his desk and made his way to the designated meeting spot.

When he was there, Riku was already waiting for him. She was humming a small tune with her eyes closed, enjoying the fresh spring breeze. As Tenn approached, she opened her eyes to glance towards him, as if she was able to sense that he was approaching.

"Tenn-nii!" She raised her hand and waved in greeting.

"Have you been waiting long?"

"I just got here a little while ago, but enough about that. I'm hungry; let's eat!"

They unwrapped their lunch boxes and opened the lid to see what their mother had packed for them. Rice was the usual staple of the Japanese, and this was prepared in the form of cylindrical rice rolls. As for side dishes, there were stewed vegetables, rolled egg omelette and meatballs drizzled with ketchup. The sight of the delicious spread was enough to make their mouths water.

"Let's tuck in!" They gave their thanks with chopsticks in hand and began to eat.

Being twins, many people tend to think that they would do things the same way. For Tenn and Riku, however, that was not always the case. For example, they way they ate was different. Tenn ate slowly, using his chopsticks to break the food up in smaller mouthfuls in a manner that could only be described as dainty. Riku, however, preferred to take larger mouthfuls, to which her older brother would remind her to chew her food properly.

"Riku, you got ketchup on your face again." Tenn frowned, taking a sheet of tissue from the packet he carried in his pocket. "Turn your head this way; I'll wipe it off for you… there we go."

"Thanks, Tenn-nii!" In response to her brother, she simply flashed him a toothy grin, not looking the least bit apologetic.

"Really now. What would you do without me?"

"Tenn-nii, you don't want to be with me?"

"You know that's not what I mean." Tenn sighed. "We don't have much time. Let's finish our food."

"Aye!"

After finishing their lunch, they replaced the cover of their lunch boxes and wrapped it up again. They would wash this at home when they returned.

"Speaking of which, do you have anything after school today?" Tenn asked.

Unlike him, Riku did not belong to any club or committee. Instead, she helped out as and when she could. She was usually with the volunteer club, where her homeroom teacher served as the club advisor. However, there were times when she would help the student council and the broadcasting committee. Tenn was part of the chemistry club, where he served as president, as well as the student council. The latter had no activities until next Tuesday.

"I promised Hanabusa-sensei that I'll help with the volunteer club's choral practice."

"For that event happening next month at the elderly care centre?"

"Yup! Tenn-nii, do you have anything on with the chemistry club today?"

"Just the freshmen's orientation and introduction session. I should be done before you."

"I see! What would you be making this year?"

As part of the chemistry club's tradition, the first day of club activities with the freshmen would be a session where the members would make something simple to be taken home. This item would be proposed by the members and chosen by the president and vice president, with the approval of the student council.

"Hand lotion. We have a lot of girls in our club and it was a popular choice. Which reminds me, you mentioned that you were running out of your supply?"

"Yup! I was about to ask you to make more for me. Tenn-nii's are the best!"

"I'll bring some back for you, then."

"Be sure to make some for mom, too!"

"Of course."

By this time, lunch break was almost over as their afternoon classes were due to start soon. Tenn sent her off at her classroom, where she waved goodbye to him as he shut the door. As usual, he had taken her empty lunchbox with him, as she would have forgotten it in school if he did not, which had happened several times in the past. He knows that he is spoiling her by doing this, but it's better than having to bring her back to school to pick it up.

Tenn usually entered his classroom from the front door, as it was closer to his seat. However, it was being blocked by a group of boys who were casually chatting, so he chose to enter by the back door. During lunch time, it was left wide open, so he simply had to walk through the doorway.

The classroom was filled with people, many of them clustered into groups and chatting away. Because of this, his silent entry into the room went unnoticed by many.

"... Speaking of which, did you hear about the little sis Nanase?"

"You bet I did. I mean, everyone's talking about it?" Now that was something that piqued his interest. "Who does that bitch think she is?"

"Really now. So what if she's his little sister? That doesn't give her the right to monopolise him like that."

"I know, right? And being weak and sickly in this day and age… does she think she's the pathetic, sad little heroine of some television drama?"

"Hilarious."

"Isn't it? It's not only Nanase-kun, but there are quite a lot of guys around who are interested in her. I'm telling you, I bet that she just feigned her illness just to be fawned over by the boys–"

The girl's sentence was interrupted by a loud sound, which was as if someone had hit something near her. As with everyone in the room, she was about to turn her head towards the source of the sound, but a familiar voice reached her ears first.

"You, over there."

"N-N-Nanase-kun?!"

"This is bad! For how long has he been listening?" Her friend who had been conversing with her whispered, feeling as frightened as she was by the way the boy was glaring at them.

"Don't you dare run your mouth off so arrogantly when you know nothing about Riku."

It was a warning, not only to the two girls but to everyone who was in the vicinity. If his words were not menacing enough, his tone had deepened so much that it alone was enough to intimidate.

In the midst of the awkward atmosphere and silence, he returned to his seat. No one knew what to do to alleviate the situation. Fortunately, they were saved by the ring of the bell and the appearance of their teacher, who yelled at them to take their seats. Afternoon classes promptly started as they proceeded with their day.

The moment the final chime rang, signalling the end of the day's lessons. Tenn wasted no time in gathering his belongings to head to the laboratory, where the chemistry club conducted most of their activities. As always, he was the first to arrive.

As he began preparing for the day's activity, the rest of the existing members slowly trickled in to help. The plan for their session went smoothly without trouble, and everyone had an enjoyable afternoon. As he had done most of the preparation, he was asked to return early, leaving the cleaning and locking up to the vice-president and other core members of the club. He took upon their offer and left first. However, he could not leave without Riku, so he simply wheeled his bicycle to the school gate to wait for her.

_I'll be waiting for you at the front gate._

He typed the message quickly on his smartphone into the rabbit chat app that the both of them frequently used to communicate. After he was done, he fished his earphones from his pocket and plugged the pin into the audio jack. He was about to slip the buds unto his ears to listen to the new album he had downloaded the night before.

However, before he could tap on the play button, someone came up to speak to him. From the uniform she wore, Tenn could tell that she was a student from the nearby all-girls academy.

She was not alone but had her group of friends with her. All of them were staring at him intensely, something that was definitely not new to him.

"Erm..."

It was troublesome to entertain them especially when he was fully aware of their intentions, but he was unable to escape. He could simply ignore them, but it would be bad to do so when they have yet to do anything wrong. "May I help you?"

He spoke to me, was what written on her face which reddened almost instantly.

"A-Ah, err, I, um!" She seemed to be unable to find the words to speak. "Y-You are N-Nanase-kun, yes?"

She seemed to know him. Another unsurprising matter.

"Yes, I am."

"Really? You're Nanase Tenn-kun?" One of her friends stepped forwards to speak to him, and she was followed by the rest. They surrounded him, eager to make conversation with him. That was all they intended to do, so he went along with the flow.

He did not need to say much, as they seemed more interested in talking to him than listening to him talk.

Less than ten minutes passed before he felt someone hug him tightly from behind, with two firm mounds pressing against his back.

"Tenn-nii, sorry to keep you waiting!" She looked up at him with a big smile when he turned to look at her.

"Well then, my sister is here so we'll be heading home."

"See you sometime again, Nanase-kun!" The girls did not seem happy that their time with him has ended, but waved him goodbye and took their leave without complaint.

The two Nanase children left school as well, after making sure that that they did not forget anything. They headed straight for the shopping district to get the strawberry tarts that Riku wanted.

"Ah, Tenn and Riku! Welcome!" The greeting was given as they opened the door of the shop, which followed the tinkle of the bell hung on it.

"Good afternoon, Mitsuki! You're not working in the cafe today?"

"The new part-time staff was able to make it today, so I was put in charge of the shop. What will it be today?"

"We would like three strawberry tarts, to go."

"Hmm, if I may make a recommendation, why don't you try the mixed berry tarts instead? It's a limited product, and I can guarantee you its sweetness!"

"What do you think, Riku?"

"I'd like to try that."

"Then we'll have that instead, please."

"Sure! Coming right up!"

"Oh, speaking of which, where's Iori?" As the twins and their mother had been regular customers of the shop, they were well-acquainted with the owner's children: Mitsuki who worked in the shop and Iori who was a younger than them and attended the same school. Tenn worked with him as fellow members of the student council but was not fond of him for certain reasons. Riku saw the boy as a younger sibling and was fond of him, much to his chagrin.

"Iori has club activities today. He should he home soon, I think."

"I see!"

"Three mixed berry tarts; here you go! That will be 1,134 yen in total!"

Tenn made payment for the treats, and they set off for home once again. However, when they reached the house, it was dark inside.

"Could mom have gone out shopping or something?" Riku suggested as she slid her shoes off.

"Maybe. She probably left us a note."

And she did, along with some money.

This was left on the dining table. On it, she wrote that their grandmother who lived outside the city had taken ill and she had left to care for her. She would only be back tomorrow afternoon and while she had made dinner for them, she did not have time to make breakfast and lunch for the next day, hence leaving them money to procure their own meals.

"Riku, do you want dinner or a bath first?"

"Dinner!"

"Got it. I'll pop the food into the microwave, so just wait for a little bit."

"Shall I help to set the table?"

"No, I'll do it. You can just relax and take it easy; I'll call you over when the food is done."

"Okay!"

Dinner was their favourite omelette rice, a common choice for the Nanase family. It was also the twins' favourite dish, and hence it was requested and made often.

"Speaking of which, isn't the variety programme which you usually watch starting soon?"

"Ah! You're right!"

Dropping her bag onto the couch, she quickly turned on the switch for the television and hit the channel's number on the remote control.

_"Welcome, everyone! Momo here! And with me, we have Yuki!"_

_"Good evening, everyone."_

_"Kyah! Look at that flawless smile! What a gentleman! And now, it's time for Re:vale's special weekday variety programme! Also known as..."_

"The food's ready."

"That's fast!" Riku moved over from the sofa, which she had been sitting on, to the dining table. "It smells delicious."

"Well, I only had to unwrap the food and put it into the microwave to reheat it, so that is to be expected. Come, let's eat. Thank you for the food."

"Thank you for the food!"

They ate while watching the programme that was currently on air. It was a normal variety show that mainly had talk segments, as well as little activities that were either pre-recorded or done in the studio. However, it was an entertaining programme even to Tenn, who did not watch television often due to his lack of interest.

At the moment, it was the main talk segment. It was led by one of the hosts, Momo of Re:vale. Tenn recognised them as the country's most famous and popular idol duo and was fond of their music. Riku had bought their singles and albums after she was introduced to them by Tsumugi, so he borrowed them from her.

"Who is that pale-looking guy? The stoic-looking one with the sharp eyes."

"I think his name is Yaotome... Raku? Gaku? I don't really remember, but it seems that he debuted recently. I think there was a rumour that he was the secret lovechild of a talent agency, but I don't have much interest in him so I don't remember."

"Hmmm, I see..."

"Is something the matter?"

"No, I was just thinking that I don't like his face."

"Even though he's kind of handsome?"

"Yup. I get the feeling that I won't be able to get along with someone like him."

"Is that so? Well, it's not like Tenn-nii would ever get to know a celebrity like him since we're just commoners..."

"Indeed."

"..."

Tenn took another mouthful of food, only to notice as he chewed that Riku had put her spoon down. The girl was making a troubled expression.

"Riku?"

"I was thinking, Tenn-nii... was it really okay?"

"Regarding?"

"Not being an idol. I mean, you remember that grim looking guy who wanted to adopt you, those years back? He said you had the talent to take the top if you were groomed properly. Not only that, Tsumugi-chan's papa wanted to scout you, didn't he? That proves that people have recognised your potential. It's a waste to not let it flourish, don't you think?"

"I'd have to disagree with that opinion. In the first place, I don't think that it's a waste."

"Why is that so?"

"I mean, I'm here, aren't I?"

"Here?"

"By Riku's side. I don't need the glory or the fame, nor do I want to stand in the spotlight. An idol has to be perfect and flawless, and you know that's not what I am. I don't want to have to create a fake me for the world to see, that people would admire and look up to. I'm satisfied with just being myself. If I became an idol, there would only be a lot of inconveniences. I won't be able to go anywhere with you anymore, including shopping, eating sweets and even to school. Riku, do you want that?"

"No, I don't want that! I like being with Tenn-nii the most, and I can't imagine having to live without being with you."

"Neither can I. That's why I decided that I will be your idol and yours alone. That is enough for me."

"Geez, why are you saying such things with a straight face?"

"Because it's how I truly and honestly feel. Does my answer satisfy you?"

"I-It's not a matter of whether I'm satisfied..." She continued eating to try to escape from the conversation, knowing that if they continued Tenn would begin to tease her.

Watching her face redden only made Tenn chuckle, and he continued eating.

The programme ended as they were done. Tenn turned the television off before placing his dishes into the sink. Riku volunteered to wash them, and he accepted her offer as he had to fill the tub for their bath. He could hear Riku singing as she completed the task.

"What song is that?" Tenn could not help but ask, as he found the tune familiar.

"It's the main song from the single from the duo from Tsumugi-chan's place! What was the name of that group again..."

"Mezzo"?"

"Yes, that! And I'm done with the dishes!"

"Have you wiped them with the dishcloth?"

"That too!"

"That's fast. The tub's not completely filled yet, so why don't you get a change of clothes first? You can bathe first, and I'll go in after you are done."

"Actually, about that..." Riku peeked her head into the bathroom shyly. "I actually have a request."

"Speak."

"Can we take a bath together?"

Even if Tenn had half-expected her to say something like that, it was a different matter hearing those words come out of her mouth altogether.

"Riku... we aren't in elementary school anymore, you know?"

"I do! But, I mean, we're alone at home now, aren't we? No one is going to know... so, please?"

Tenn knew that tone of voice well enough. Whenever Riku requests something in that manner, it was akin to him being offered something from a devil. It was a great temptation, which had dire consequences. While he was aware of that, he would never be able to refuse. If he had, Riku would have stopped making selfish requests a long time ago.

"Riku... we can't." His shaking voice was nowhere near convincing, but he had to be the one to take responsibility. After all, he was the older one between the both of them.

"Tenn-nii, please?" She wrapped her arms around him, pressing her upper body against him.

This was no longer at the level of begging, but rather seducing.

Tenn could feel a blush rising on his face. It was no good at all. With the way she was looking at him, even thinking of refusing her now became impossible.

"Fine, you win."

"Yay!"

"But we're only going to bathe. Nothing else. Look, the tub's filled now, so let's get our clothes so we can get into the tub while the water's still warm."

"Sure~"

Watching her leave the bathroom so happily, Tenn felt bad for having some regrets about his decision. However, he gets the feeling that this will go in accordance with his expectations. Not in a good way, perhaps.

He returned to his room to get his pyjamas and a pair of briefs to change into after his bath. When he returned to the bathroom, Riku was already there and changing out of her clothes. Specifically, she had already removed her skirt and unbuttoned her blouse, which she was removing off her person. That left her in her underwear: a white bra decorated with lace and simple white panties with pink polka dots.

"Ah, Tenn-nii!" She did not seem the least embarrassed to be seen by him in that state, it seems. "What took you so long?"

"You're just too fast." At this time, Riku had begun to unhook her bra, and Tenn turned around to avoid looking at her. "Riku, make sure you wrap a towel around yourself."

"Why?"

"So that you don't catch a chill in the bath." It was a fact, but it was also a lie.

"Oh."

"You get in the bath first; I'll join you later after I change."

"Got it!" The opening of the sliding door was heard, and soon it was shut.

Tenn could finally let his tense shoulders relax. She definitely did that on purpose, he thought but did not want to believe.

After removing his clothes, he also wrapped a towel around his waist before entering the bathroom. Of course, he made sure that he was calm before he did.

When he opened the door, Riku had just finished rinsing the shampoo out of her hair and was applying conditioner onto the tips. "Ah, Tenn-nii! You sure took a while."

"I had to use the toilet." That was the fastest excuse he could come up with, but at least she bought it.

"Ahh, I see."

Tenn turned the nozzle of the shower towards him and wet his hair. He poured some shampoo onto his palm which he massaged onto his scalp. He had just finished rinsing it off when Riku made another request of him. "Tenn-nii, could you help me wash my back?"

She had already removed the towel and turned her naked back towards him. It was similar to a scene in a romantic comedy, and if Tenn had been a character in that series he would have gotten a nosebleed.

"R-Riku, you can do that by yourself, can't you?"

Calm down, Tenn, calm down; was what he willed himself, but it did not seem to be helping.

"I want Tenn-nii to do it for me."

"You..." He could only let out an exasperated sigh. This was definitely not the first time she had tried to seduce him, but each time was different and both expected and unexpected in their own way. "Pass me the soap and sponge; I'll do that for you."

"Here you go!"

When she turned to hand it to him, she had covered her chest with her arm. However, he could see the curve of her well-developed breasts well enough and that made him blush.

"Tenn-nii, are you going to start?" He did not realise that he had been staring, and Riku's question made him snap out of his daze.

"I'm getting to it."

He quickly lathered some of the soap onto the sponge before raising it to her shoulder. "Let me know if I'm too rough."

She nodded in response, and he began. He began her shoulders at the top, from left to right and slowly, down. The soapy sponge slid across her soft and supple skin easily. It must have felt good to Riku, who let out a pleasant hum.

Tenn finished the task quickly and grabbed the shower head, washing off the white lather with the warm water.

"There we go."

"Thanks so much, Tenn-nii! Ah, I'll be going into the tub now!"

"Be careful not to slip on the wet floor."

He was conditioning his hair when he heard Riku let out a happy sigh.

"The water feels great. You should come in soon, Tenn-nii."

"After I'm done washing off." He took about ten more minutes to finish that, and once he was clean he got into the water as well.

Their family's tub was larger than average, as their mother wanted one to be able to fit the entire family. Tenn settled into the warmth of the water next to Riku, who had her back against the edges with her eyes closed.

"You aren't asleep, are you?"

"I'm awake!" She assured him, popping her eyes open to look at him.

However, she did not expect that he would he sitting so close to him and made an expression of surprise. To Tenn, it looked nothing but adorable, which made him laugh. Seeing this, Riku pouted with a little huff. It was only for a short while before she inched closer to him, so that their arms were touching, and leant her head on his shoulder. He does not shrug at the contact, comfortable with the proximity.

"Tenn-nii?"

"Hmm?"

"I was just thinking that being with you makes me the happiest."

"How many times have you said that already?"

"I'll definitely keep saying it because it's the truth!"

"You silly girl..." He answered as he placed his right hand over her left, holding it gently under the water. "It's the same for me, you know."

"That you'll repeat yourself over and over again?"

"Of course not." If it is one thing that anyone should not intentionally make Tenn do, it would be to make him say the same thing more than twice. "It's about being the happiest when I'm with you."

"Ehehe... Tenn-nii's words always make me blush." She gave him a sheepish grin. "But it always makes me really happy in here."

She raised her right hand and placed it over her heart. "You know, Tenn-nii... back when I was always in the hospital, I used to think that the world was a cold and lonely place. I mean, I spent most of my time in there than at home or anywhere else. However, Tenn-nii visiting me was something that made my world brighter and changed it. Even if it was about the little things that I thought was boring and mundane, you would listen to everything I had to say. Because of this, I began to reconsider and search for meaning in my life. I was able to become who I am today because you were always by my side."

Without letting go of his hand, she moved to face him, taking his other hand in hers. Her expression was tender, her gaze soft and loving.

"That's why I'll say this over and over again: Tenn-nii, I love you."

And Tenn knew exactly what she meant by that word. It was the same thing that she had said almost two years ago. That day, they were also left alone at home, when both of their parents had left on an overnight trip their mother had won in a lottery in the shopping district. He remembered the incidents of that day clearly: he had been in a bad mood because of insensitive things that were said about her by the boys in her class. Riku had mistaken this as him being angry with her, and because he refused to speak about the matter she had to corner him, quite physically too, to talk.

At that time, Tenn had already known that his feelings for Riku were more than just that of a brother towards his sister. However, he knew that it was something that was abnormal and kept it to himself, even trying to pass it off as a misconception. In the end, his efforts were futile and he was unable to shake it off. However, he placed protecting her as his utmost priority. Who would not want to the same if it was regarding their most precious person?

After being pressured by her to speak, Tenn finally explained the reason why he had been acting unlike himself. However, because he spoke without thinking, he unintentionally revealed his true feelings through his tone and choice of words. He only realised this after he had finished. As he had sworn to keep them buried and take to his grave with him.

However, Riku accepted them, saying that she loved him, too.

At that time, he was in a panic and was unable to think properly. He dismissed her confession as something that was in response to his blunder, that she loved him because they were family. That had made her angry, and she slapped him for the first time. While that was a complete surprise in itself, what she did next was something even more unexpected: she kissed him, on the lips.

When they were still young children, up to the first few years of elementary school at least, they did share kisses on the cheek or the forehead. But oblivious is something Tenn was not, and he knew that the meaning of this kiss was completely different from any of those.

At that moment, it felt like a dream. His shoulders felt lighter as if he had been released from a heavy burden that had been weighing him down for much too long. When Riku pulled away from him after the first kiss, he quickly grabbed her wrist and pressed his lips to hers once again. He could not remember how many times they kissed that evening, but at that time he felt that the both of them would die if they let their lips part for far too long.

The only thing he knew was that when they finally grew tired of kissing, she was lying on his bed, panting for air with her cheeks flushed red and appearance dishevelled. It was a sight that could only be described as erotic, much more so that in many of the dreams of her that he had seen over the past years.

At that point, his brain went into autopilot and nearly hit the panic button. The only reason why it did not was because Riku had, for the lack of a better term, seduced him. That day, the both of them gave in to the passion that was no longer held back, crossing the line that they would never be able to return to. They made love to each other, allowing their bodies to join as one.

Tenn only grew fully aware of what he had done and the consequences behind it when she had passed out. This was when she had come, which was before him. He stopped immediately when he realised that she had lost consciousness and panicked, but his worry was for nought as she had simply fallen asleep. To note, he took care of himself in the toilet afterwards, making a mental note to invest some of his allowance on a box of condoms.

He had no inkling of what compelled him to act that way. Blaming his teenage hormones was the worst excuse he could have come up with, but he did not know how to explain himself. However, watching her sleep peacefully made all his worries and regrets dissipate. All he could feel watching her was a gentle tightening of his chest: love, and perhaps happiness. These, he believed, he did not deserve. However, when she woke up and smiled at him warmly, that feeling in his chest only grew stronger.

Regardless of how far they have gone in their... well, relationship, Tenn was fully aware that it should not be allowed to change. They had just started high school and had no power or ability to stand on their own two feet. If he wanted to protect Riku and make her happy, he would choose the best option, even if it was harsh. He promised himself that he would only allow them to become lovers when they have graduated and become independent.

Despite that, somehow Riku had always managed to successfully breach through whatever form of control he had put in place for himself. Whether it was intentional or not, or both, he does not need to know. To be honest, it was tiring having to stave off each little trick she pulls when the chance of succeeding was not a hundred percent. He still tries, and at times, fail.

There had been times, such as their current situation when he would completely give in to her advances.

"Riku..."

"Tenn-nii, one, please?" He knew what she wanted, and would give it to her. From the time that he had chosen to go along with this, he had lost the option to refuse or escape.

Tenn, too, moved his position to one was more comfortable. Noticing this, Riku spread her legs apart, allowing him to sit between them in order for them to be in closer proximity to each other. With both their hands held together, fingers entwined, he leant forward to kiss her.

It was a gentle kiss, but a tender one. He knew that Riku preferred their kisses to be slow and sensual, yet still overflowing with passion. He did not appreciate rough kisses either, so it worked out for the both of them.

When they parted, he could feel his heart beat faster. The heat that he could feel on his face was definitely not just from the bath water. "You can't be satisfied with just one, can you?"

"May I have more, then?"

"You didn't need to ask," was Tenn's reply before he allowed their lips to connect again.

The second kiss was more passionate than the simple one he had given her the first time. Riku had let go of his hands to wrap her arms around his neck, bringing their bodies much closer together.

With his hands now free, Tenn was free to do as he pleased. He first placed her hands on her hips beneath the water, and slowly moved it up her side. He followed the rhythm of the kiss as he did this. When he reached her underarms, he moved them down again, but not completely. Instead, he stopped at her chest, where his fingers trailed under her breasts and cupped one in each palm.

Riku let out a small gasp in the kiss when his fingers began to play with her nipples, teasing them by pressing and moving them in a slow, circular motion.

"Tenn-nii..." She wailed after breaking the kiss when Tenn had begun to massage her breasts while his thumbs were still moving. "It feels good."

"Shall I make you feel even better?"

She nodded her head with a small sound of approval. Tenn coaxed her to release her hold on him and lean backwards, his hands supporting her back as he moved his body lower. Her chest was now out of the water and completely exposed to his sight.

Lowering his head, Tenn stuck his tongue out to prod one of the buds. He did not give time for her to experience that sole sensation, as he continued by sweeping his tongue across the areola. As he did this, he allowed her to ease into a comfortable position before removing his hands. His left, now able to attend to the other breast, continued its work. He could hear Riku try to suppress a hum of pleasure when he began to suck on the nipple.

"Riku, let out your voice." That line was not to instruct or command her, but rather his way of seducing her.

His right hand was now free, but that does not mean that it did not have a task to do. He ran those fingers down her stomach, past her navel, to reach the area between her spread legs. Riku shivered slightly as she felt her fingers approaching her abdomen, but it was from the anticipation of what he would do to her next.

His fingertips grazed the sensitive skin, tracing the folds of her opening lightly. However, he had yet to put them in, and it was on purpose. With his forefinger, he traced the opening from the top down and back up again, rubbing the clit when he did.

"Tenn-nii, please!" She begged, but he wanted to tease her for a little more.

However, he had forgotten that she was no longer someone who would simply sit by and wait for what she wants. That was why she would not remain helpless and let him do as he pleased.

This time, it was Tenn's turn to let out a gasp in surprise.

"Riku!"

What she had done was to curl the fingers of one hand around his aroused, but not yet hard, dick. Her movements were slower than usual because it was underwater, but she still managed to catch him by surprise. She moved her hand up and down, pumping the organ to full erection.

In the meantime, Tenn did not remain idle. After getting accustomed to Riku's touch, he continued with pleasing her. However, he did more than teasing and rubbing this time. Since she had done her best for it, there was no reason why he should continue to deny her of what she wanted.

He raised his head to kiss her once more, guiding her to lean forward towards him so that her breasts were pressing against his chest. This made her raise her body upwards, especially her hips, and he used this to slip his hand between her legs to slide his middle finger into her. As she had already been aroused, it went it easily, but the sudden intrusion had still made her let out a moan.

The digit that was inside her did not remain idle for long. Having done it several times before, Tenn knew how Riku liked to be fingered. He first curled the finger to stretch the walls of muscle and to allow her to get used to its presence, preparing for the entry of a second which was inserted soon after.

Tenn began to use those two fingers to rub against her inner walls, aiming for her favourite spot. When he was able to hit it, she made small mewls in pleasure in response. However, that does not mean that she was satisfied.

"It's not enough, Tenn-nii... give me more!"

In reply to that request, a third finger was added, and he began to move them in a pumping motion. The long digits slid in and out of her easily, as they were covered in her body's natural lubricant.

Riku did not hold her voice back, moaning loudly with her arms wrapped around his neck a second time. Following the rhythm of his fingers, she moved her hips accordingly, which made her want to tease him. "Can't wait for the real thing? This can't be enough for you, can it?"

"Of course. It feels really good, but there's no way it can compare... say, Tenn-nii, put it in me?"

"Not yet, Riku, not yet."

"Tenn-nii's always teasing me like this... it's not fair!"

She would have given him one of her usual pouts, but she was unable to as the tell-tale sign of her climax approaching dominated all of her senses. Tenn noticed this as well and moved at a faster pace. With a cry, she came with his fingers still inside her.

Tenn quickly withdrew his fingers as he prepared to catch her as her body went limp after that moment, supporting her with his upper body. "You okay?"

"Yup… just the usual. Nothing to worry about." She gave him a smile. "I'm good to continue."

"You don't have to push yourself."

"But it has been too long since we got to go all the way. Who knows when would we get another chance to?"

"I understand what you mean."

"That aside... you're still hard, aren't you?"

She was right, and he had not forgotten about it. He was still very much erected, and it seemed like it wasn't going to go flaccid anytime soon.

"Shall we move to the bedroom, then? We'll continue there. Just wait here, I'll go get a towel."

"I don't want to."

"Eh?"

"Can't we do it here?"

"Riku, do I look like I keep my store of condoms in the bathroom?"

"We don't need one; you can just put it in just like that."

"No."

No, no, no.

Tenn could relent to many of her requests, but that was the one definite thing he can and will never agree to, regardless of how tempted he was. The risks were much too high, and he knew well enough then to do something that dangerous as he was fully aware of the potential consequences. He refused to let one rash act ruin her entire life and future, even if it as a slim chance or may have a positive outcome.

"Why?" Her expression reflected both her confusion at his refusal and her displeasure with being rejected. "It's fine, isn't it?"

"It's not. You know why we can't do it here. What if you get pregnant?"

"I won't! It's a safe day after all."

"Despite that, it is the one thing I cannot agree to. Safe or not, we can't guarantee that nothing will happen. We're still in high school, and will be taking our entrance exams for college before we know it. I don't want risk anything in your future just because of one rash act. We could always do that another time... at least when we are old and ready to bear the consequences. That is why I will not concede this time. Do you understand?"

Tenn had made his point clear, and Riku was able to understand. She knew that she was often making selfish requests of him and that he would give in to her even if he initially disagreed. However, she was not irrational.

"I do understand, Tenn-nii. I'm sorry for asking something so unreasonable."

"Thank you for understanding, Riku." He pressed a light kiss to her forehead. "Shall we move to my room?"

She nodded in agreement. Tenn stood up and stepped out of the tub, offering her a hand to help her when he was out. She took it firmly, and carefully followed him out.

Outside the bathroom, he quickly grabbed a towel to dry her hair, trying to get most of the water out. After he was done, he wrapped her in it before scooping her up into his arms. Riku had not expected that Tenn would literally sweep her off her feet and let out a yelp in surprise, but did not complained as he carried her princess-style up the stairs to his room.

He first laid her down gently on his bed, turning to his bedside drawer to search for the box of condoms he had hidden in it. He retrieved one packet from the box, noting that he would need to get a new box soon.

He turned back to Riku, who was ready and waiting for him. "Riku, do you want to be on top this time?"

"Really? I can?"

"Sure."

Of the several times that they did it, Tenn only had Riku ride him once. Perhaps it was due to the flow of events or the way she liked it, he was always the one to take the lead, which led to him being the one on the top of the position they happened to get themselves into. Of course, the only exception was their first time, when she had been the one to take the initiative.

It never crossed his mind often to let her lead, often because they rarely had the luxury of time. Riku was demanding, and he would answer to whatever she wanted quickly. It was a bad habit of his, admittedly. However, this time, they did not have to worry about running out of time or any chances of being caught.

So, why not, was what he had thought when he proposed the idea, and he was relieved that she was not repulsed by the idea.

When he sat down at the edge of the bed, he prompted her to sit up from her lying position. He offered a hand to help her up, but she got up without any problem or delay. In fact, the way she moved looked as if she had jumped or bounced up.

"You're being too excited about this, aren't you?"

"But it's the first time Tenn-nii let me do something like this. Ah, should I put this on for you?"

"No, it's fine." The one time he had let Riku do it was his only regret.

It was quite the unforgettable experience. Unlike him, Riku was known for her butterfingers and clumsy coordination. The last time he let her put the condom on it, she could not get it done right, and the fuss had made him come while she was still fumbling with the piece of thin latex.

Tenn quickly rolled the condom over his erection, so that they could get into position without wasting a second. He leant back onto the fluffy pillow while Riku flanked him in a squatting position, which gave her more leverage.

Her face was flushed, the rise and fall of her chest a clear indicator of her anticipation. She was begging him with her expression alone, waiting for that moment when he would tell her that he was ready. He knows that he had made her wait long enough; he himself was no longer able to wait. He took her left hand in his right again, their fingers held tighter than before.

"Riku, go ahead."

She nodded in response, face brightening up in joy.

She lowered her hips slowly, using her right hand to properly guide her descend to where his body was to connect with hers. Tenn watched as she used that hand to spread her entrance apart so that he could enter her easily. The tip slid in easily, followed by the rest of the head. Both of them let out a moan at the moment of penetration, which continued as she took all of him into her.

"Wow..." she breathed, feeling the fullness of his length and girth in her. To her, it felt almost as if he was throbbing inside of him, and it was certainly the most amazing feeling. "Tenn-nii, can you feel me?"

"Yes, I can." Tenn's voice was as breathy as hers. "It's hot, but it feels so good inside of you."

"Having Tenn-nii inside of me is the best, too." She rolls her hips once, pushing down on him and making him wince. "Maybe it's because of the position, I'm feeling Tenn-nii more than usual."

"I can't get enough of this."

"I know, right?" She looked smug for some reason, but he will let that pass. "Tenn-nii, can I move?"

"Whenever you're ready, go ahead."

Despite what Tenn said, Riku took his words as a go-ahead and did not bother waiting. She raised her hips and body upwards, lifting herself out of him. He placed both his hands on her waist to help her to keep her balance, while hers were placed palms flat on his lower torso. She raised her position as high as where the head was, nearly having the tip out of her, but lowered them back down again. She repeated this movement slowly, trying to keep a steady pace. As she did so, she let out a string of small 'ahs' along with her pants, her sweet voice soon becoming the only sound that he could hear.

However, Tenn was not one to just lean back and let her do all the work on her own. She was trying to make an effort to make the both of them feel good, and so should he.

The next time she brought her hips down towards him, he thrust his own hips up. Perhaps he may have misjudged the distance or her speed, but it was as if he had slammed into her at full force. Despite that the cry she let out did not seem to be one of pain, Tenn still worried.

"Sorry, was that too rough?"

"No, I was just surprised, that's all."

Relieved that he did not hurt her, they continued. However, it did not seem that Riku could not keep her pace after a minute or two, which led Tenn to offer a suggestion. "Riku, lean towards me?"

She did not seem to understand what he was about to do but was willing to follow his instruction. She was feeling a little exhausted from having to exert herself, and she was grateful that Tenn never failed to notice that.

She pulled off him first, before shifting her legs to balance on her knees, a more comfortable position that allowed her body to be closer to his. Rather, she was just lying on top of him, with little or no space in between them. "Like this?"

"As long as you're comfortable."

"Which I am."

"That's all that matters." He snaked one hand around her hips so that she would not move so that the other could help him re-enter her.

It was done with practised ease and their bodies were connected once again, but not fully sheathed. He brought his other arm around her as if he was hugging her. Before he continued, he stretched his neck up to her for a kiss, which she obliged. Their lips were still locked when he pushed himself into her and began to move in and out of her in a slow, rhythmic pace.

When they parted, Riku began to call out his name sweetly, wrapping her arms around his shoulders. She begged for him to move faster, to pound into her harder. As she did, her hips started to move in sync with his movements, meeting his thrusts at just the right moments.

By this hour, the sun had set long ago. In its place in the sky was the moon, and it was full and bright tonight. Its light shone through the glass of the closed window, between the gap between the half-closed curtains, onto their naked bodies. It made their sweat-stained skin seem as if it was glistening. In Tenn's eyes, the physical figure of the one and only girl he loved was that of a nymph's… stunning, ephemeral and absolutely beautiful.

He felt blessed and extremely fortunate that she was his, that she had chosen him over others.

As a child, he had caught sight of a television programme that spoke about twins of separate sexes being lovers in their past lives. He was too young to understand the true implication that word; to him it meant that Riku was the most important person in his life. Despite the ways their relationship had changed since then, that was one thing that stayed the same.

After a little while, they could both feel that they were reaching their limits. Unlike Riku, who was more vocal at the beginning and would be unable to let out many sounds other than moans as she approached her climax, Tenn only began to let out more than grunts and pants when he was close.

He came before her, moaning out her name as he released his load into the condom. She could feel the heat of his liquid cum through the thick barrier, and how it filled the latex sheath. It felt good, and because of this, she came after him.

Panting for breath, the two lay where they were. Neither felt compelled to move, allowing the feeling of their release to leave their bodies. When it did, Tenn slowly pulled out of her, quickly collecting the used condom to dispose of it.

"Say, Tenn-nii, think we could go for one more round?"

Of course, Tenn had no reason to refuse, aside from not wanting Riku to overexert herself. Despite that consideration, he decided to agree.

He made her promise that their second round would be their last, and the deed was done without haste. However, it seemed that it may have been too much for her to take, as she had fallen asleep right after coming for the third time that evening.

Not wanting to wake her, Tenn got a towel to wipe her down, helping her to put on her undergarments and pyjamas before carrying her to her room. He turned on the air conditioner, mindful of setting the temperature to a comfortable one, meaning that it was not too cold, to avoid aggravating her condition. Covering her body with her fluffy blanket, he tucked her in, stroking her hair and cheek gently with a small smile. When he left her room, he closed the door gently behind him, not wanting to wake her up.

"Good night, Riku."

At this moment, Tenn was a little exhausted, but not the least bit sleepy. While letting the bath water drain, he took a shower to get rid of the sticky sensation left on his skin from the sweat. When he was done, he felt like having something sweet. That made him remember the mixed berry tarts they had bought. However, he wanted to eat them with her and decided to head out to the nearby convenience store to purchase something instead.

Their side of the neighbourhood was quiet at that time of night, as it was further away from the train station. As he made his way to the store, he passed by two salarymen who looked like they had just been made to either work unnecessary overtime or accompany their superiors at a drinking session.

The convenience store was rarely sparsely stocked due to the diligence of the employees. However, at this hour there was not much of a choice to make. Tenn was debated between jelly and pudding but ended up going for the latter. He also bought a loaf of bread for breakfast, having noted that they were out of it, along with some other ingredients. Their mother was a scatterbrain and it was not uncommon that she would forget to stock up on the groceries.

However, he did not expect to have bumped into someone he knew outside the store when he was leaving. He glared at him the moment their eyes met, but as the younger person, he knew it was proper manners to offer his greetings.

"Good evening, Kujou-san."

"If it isn't Nanase Tenn. Good evening. It has been five years, hasn't it? I believe you are in your final year of high school now?"

"Yes, I am."

"I see. That is good to hear. You seem to be doing well. I presume it would be the same for your precious little sister… what is her name again?"

Tenn's frown did not disappear, especially since it was obvious that the man… Kujou Takamasa was trying to drag out the conversation. That, he had no intention of continuing.

"Ah yes, I remember now. Riku, was it? Heaven and earth. How ironic."

"Riku is well, thank you for asking." Tenn's tone was dry. "What brings you to this humble neighbourhood at this time of night?"

"Business, of course." With him, it was hard to tell of it was the truth or a mere lie, but Tenn remained sceptical. "Indeed, it is such a pity."

"A pity?"

"You have grown up well, into a handsome and dashing young man as I had expected. You would truly be able to become a popular idol if you had decided to be a good child and listened to me."

"If being a good child means abandoning my family to follow you, I'd rather be seen as being otherwise."

"Don't snap at me like that. I was simply implying that it was a waste not to nurture and bloom the talent that you were born with. I'm sure that, given a different circumstance, you would have chosen to come to me. However, that does not change that you, Nanase Tenn, were made for the entertainment industry. Even if you did not make the cut to be an idol, which I'm confident that you would, you may have made a good producer."

"A producer… you say…"

Somehow, that was a surprise to Tenn. When he was first asked to consider his career path, he had actually considered becoming a producer. Even though he did not feel compelled to watch television programmes like his sister, he often watched them with her and was often amazed how people were able to come up with so many ideas and ways to entertain viewers, who could only watch them from behind a screen.

How did this man manage to know what he was interested in, was the actual surprise.

"… I may take up on your suggestion."

"Oh? You finally feel compelled to become an idol?"

"No. The latter."

"Ah, that… well, if you are truly interested, I do know of a good volitional school. What you learn there would definitely be more useful compared to a regular university, but their admission criteria are known to be quite strict. Shall I write a recommendation for you?"

"No, thank you. I will get in by my own ability."

"You are a stubborn child, aren't you? But, I don't dislike that. I shall bid you farewell for today. I'm sure we will meet again, soon."

"I hope we don't," Tenn muttered under his breath, watching the man turn to walk towards the station.

Feeling the chill of the evening spring wind, he quickly retreated back to the warmth of his home. He put the groceries away before settling on the couch to enjoy the pudding he had bought, catching the later half of a music programme on television to pass the time. He turned the television off when the credits began rolling, washing the plastic cup before disposing it into the recycle bin in the corner of the kitchen.

Finally feeling sleepy, he decided it was time for bed.

He first brushed his teeth, and when he was done, turned off all the lights in the lower level of the house before heading up to his room. He changed into his pyjamas but did not settle down into his own bed. Instead, he decided to cuddle up with her in hers.

While many knew that Riku was the more selfish and demanding of the two, but that did not mean that Tenn did not have demands of his own. In fact, he was more insistent about his demands than his sister was: instead of waiting for or forcing others to gratify his desires, he would rather take matters into his own hands and take action.

Fortunately, the mattress was enough to accommodate the two of them. This was not the first time they had shared a bed; it was something that happened often, and in secret from their parents.

"Tenn-nii?" He heard her mumble when he lay down next to her.

"You dozed off earlier. Get back to sleep; it's late."

"Okay." She wriggled closer to him, snuggling up to his clothed chest. She probably thought of him as a hugging pillow or a source of warmth in her half-asleep state.

Tenn put one arm around her, getting into a comfortable position to rest in. He let out a large yawn, letting his eyelids flutter close.

As always, it had been a long day, but somehow it felt like an ordinary one. It was fun and fruitful, and he believed that he felt this way because he spent these days with her. However, he knew that these rainbow-coloured days, which they take for granted, may not last long. After high school, they would probably go their separate ways. They may end up finding someone else they are interested in and fall in love, perhaps get married to that person and start a family.

Tenn did not want that. If only they were not siblings, he would not have to worry and be insecure. He would be able to boldly and openly profess his love for her, and make her his.

Riku, being Riku, probably did not think about complicated things like these. She always seemed to be free of worry, which was why she could smile in a carefree manner. He saw nothing wrong with that; as it makes him smile as well.

Abandoning the family and leaving her side? The present him would never be able to do something like that.

In the past, he had considered Kujou's proposal and was willing to accept it. However, her tears were what made him change his mind. He had no regrets, however. Life was not easy for their parents, but even without the sum that Kujou had offered him, they managed to get by. They were fortunate to have relatives who were more than willing to help with Riku's hospital bills, which put her on the road to recovery. Paying them back the money was something that would take a while, but they could manage. Tenn himself intended to get a scholarship, which was not impossible with his grades.

However, there was no use talking about the future if one does not focus on the present. That is why he will treasure the remaining days he spends with her. Rather than a special time or event, he will always treasure the mundane every day that passes naturally with the flow of time.

These days, filled with smiles and laughter, will shine brighter than the purest and most precious of diamonds.

**\- END -**

**Author's Note:**

> Actually, I was really stuck at the R18 part and took to long, to the point that I actually lost my patience. To be honest, I was thinking "経験がない処女がエッチを書くことは大丈夫かな" (will it be okay for an inexperienced virgin to write smut) while typing away the entire time. Then again, this isn't my first time; I shouldn't be griping.
> 
> That aside, I hope this fic upholds the original work/idea? I wanted to cover more but if I did that it would be overkill.
> 
> Thanks for reading!

**Works inspired by this one:**

  * [Dirty Little Surprise](https://archiveofourown.org/works/12912456) by [amamiya_toki](https://archiveofourown.org/users/amamiya_toki/pseuds/amamiya_toki)




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